We have just bought an Acer 200 Tablet with GPS that we were hoping to use as back up chart plotter both in the Caribbean (we are in the Eastern Caribbean over the winter on our Bayfield 36 and the Great Lakes in the summer on our trailerable sailboat). So far we have not found apps ...Imray for the Eastern Caribbean seem to be available for the IPAD but we are not finding them for our Android and the same for the Great Lakes. Should we be returning our Acer and buying an Ipad?

Really? an electronic back-up for your electronic chart plotter ?You do tripple back up with paper I assume. Apps and Crapps is only as good as the device it is on. Paper will weather voltage drops and flops on the floor, it will even survive a good soaking. So one electronic device is your GPS, Chartplotter, AnchorAlarm and Communication System ? To risky for me!

iNavx is by far the best of the ones I have used for iOS, at least for North America and the Caribbeans.

Speaking of backups for a chartplotter I just chartered a boat in the Med, and the chartplotter failed on the 3rd day. As much as I believe in paper charts as a last resort, I was happy to have an iPad with me! Just makes it so much easier.